Such a clamping system is indicated in DE 102007024552 A1 or DE 102006055422 A1. FIG. 1 shows the clamping system also known as a 4-point clamping system. The clamping system 10 has the function of detachably connecting two preferably rotationally symmetrical parts, of which one part 1 exhibits a preferably cylindrical or conical hollow shaft 2, and the other part 3 exhibits a receiving portion 4 for receiving the hollow shaft 2 with a precise fit. To this end, the clamping system 10 has a main body 11 that is concentrically arranged in the receiving portion of the other part 3, extends into the hollow shaft 2 of the one part 1 when the two parts 1, 3 are joined to each other, and bears two diametrically arranged clamping bodies 12, which can be adjusted in a diametrically opposed manner between a release position and a clamping position (see FIG. 1).
Given an activation in the direction of the clamping position, the two clamping bodies 12 run onto a continuous wedge flank 5 provided in the hollow shaft 2 of the one part 1 and formed by a back-cut clamping shoulder, thereby exposing the hollow shaft of the one part 1 to an axially directed contact force in the direction of the other part 3, and pulling it into the receiving shaft 4 of the other part 3, until a front-end radial annular surface 6 of the inner part 1 hits an opposing front-end radial annular surface 7 of the other part 3. With the two parts 1, 3 joined together, the two clamping bodies 12 not only ensure that enough axial contact force is generated, but also that the hollow shaft 2 of the one part 1 undergoes a certain radial expansion, which offsets the accuracy of fit between the hollow shaft 2 of the one part 1 and the receiving portion 4 of the other part 3, and improves the alignment of the two parts 1, 3. When the two parts 1, 3 are joined together, the hollow shaft 2 of the one part 1 is thus received in the receiving portion 4 of the other part 3 with a tight fit.
Given an activation in the direction of the release position, the two clamping bodies 12 are disengaged from the back-cut shoulder in the hollow shaft 2 of the one part 1. However, the tight fit maintains a tension between the hollow shaft 2 of the one part 1 and the receiving portion 4 of the other part 3, which hampers or even prevents a detachment of the two parts 1, 3.
For this reason, the clamping system indicated in the publications mentioned above has an ejector 13 whose function is to separate the compression bond between the two parts 1, 3 when the two clamping bodies 12 are activated in the direction of the release position. The ejector 13 here consists of two parts. In particular, it is made up of a tubular element 14 and a ring element 15 that envelops the tubular element 14. The tubular element 14 is anchored in the main body 11 by a type of bayonet coupling. The ring element 15 envelops the tubular element 14, and is held in the main body 11 by the tubular element 14 in such a way that it can be axially displaced together with the tubular element 14 for an ejection stroke corresponding to the aforementioned axial play for the ejection process. Given an activation in the release position, the clamping bodies 12 run up onto two wedge flanks 17 provided on the ring element, as a result of which the ring element 15 is exposed to an axially directed ejection force in the direction of one part 1, and presses the one part 1 away from the other part 3. Therefore, the actual ejection function involves the ring element 15, but not the tubular element 14. While the tubular element 14 is taken along by the ring element 15 in the ejection direction, it exerts no ejection force on the one part 1 to be ejected. The two wedge flanks 17 of the ring element 15 are formed on axial extensions 18 of a ring body 16. When the ring body 16 is situated in the centric receiving opening 19, the two axial extensions 18 are positively accommodated in two diametrically opposed, axial driving grooves 20 in the main body 11. The positive accommodation of the two axial extensions 18 in the driving grooves 20 prevents the ring element 15 from twisting in the main body 11, but at the same time ensures the axial displaceability of the ring element 15 required for ejection.
The clamping system 10 indicated in the publications mentioned above has proven itself in terms of function. However, it is still in need of improvement with respect to production. While the centric receiving opening 16 for accommodating the ring body 16 can be fabricated from a production standpoint in an easily initiated drilling process, generating the two eccentric driving grooves 20 for accommodating the two axial extensions 18 requires that the main body 11 be additionally milled. The additional milling of the main body 11 combined with the two-part structure of the ejector 13 comprised of the tubular element 14 and ring element 15 increases the production outlay, and hence the manufacturing costs of the clamping system as a whole. Aside from that, assembly of the ejector 13 and its installation into the main body 11 requires time and technical skill.
Proceeding from the prior art discussed at the outset, i.e., the clamping system illustrated on FIG. 1, the object of the invention is to provide a clamping system, in particular a 4-point clamping system suitable for MQL (minimum quantity lubrication) technology, which is distinguished by a functional structural design that has been simplified in terms of production and assembly.